Data can be recorded on and read from a moving magnetic tape with a magnetic read/write head positioned next to the tape. The magnetic “head” may be a single head or a series of read/write head elements stacked individually and/or in pairs within the head unit. Data is typically recorded in tracks on the tape by moving the tape lengthwise past the head. The head elements are selectively activated by electric currents representing the information to be recorded on the tape. The information is read from the tape by moving the tape longitudinally past the head elements. Magnetic flux patterns on the tape create electric signals in the head elements as the tape moves along. These signals represent the information stored on the tape.
Typically, data is recorded on or read from each of the parallel tracks on the tape by positioning the head elements at different locations across the tape. Head elements are moved from track to track either to record or to read the desired information. A head position actuator operatively coupled to servo control circuitry can control movement of the head according to servo information recorded on the tape.
Servo circuitry is able to position a head with respect to a tape if the lateral position of the tape is suitably restricted. Tape guides (or rollers) with flanges often are used to restrict the position of the tape. However, flanges can cause very rapid tape motion across the tape (laterally) and down the length of the tape (longitudinally) when the tape edge gets caught on a flange or on a surface imperfection thereof. Flanges can also cause excessive wear on the edge of the tape. Conversely, the sharp edges of the tape can, over time, cause excessive wear on the flange, itself. The tape sometimes curls at the edges when it touches the flange. This curling further destabilizes the lateral position of the tape.